The invention relates to a key module or push button switch comprising a bell-shaped or dome-shaped key member formed of elastic material which has an edge limiting its open side. A plastic housing part is provided which partially accepts the key member and into which the key member can have its closed side previously inserted. Outwardly directed shoulders are provided on the key member in the proximity of the edge thereof which engage into recesses provided at right angles to the axis of the key member in the plastic housing part.
Such a key module is already known from German Utility Model No. 83 34 679, incorporated herein by reference. In this known key module, the shoulders which engage into recesses in the plastic housing part serve for the purpose of retaining the key member in the plastic housing part in an uncomplicated fashion. Thus, a composite member formed of the key member and plastic housing part which is simple to manipulate is formed.
In the mass production of such key modules, the insertion of the shoulders of the key member into the recesses of the plastic housing part is not simple, since the bell-shaped or dome-shaped key member formed of elastic material must be elastically deformed for this purpose.